基本介绍
Aggregation是Trident的基本基本api 主要作用是聚合，如下聚合方法作用是记录单词出现的次数
package com.storm.trident;
import org.apache.storm.shade.org.apache.commons.exec.util.MapUtils;
import org.apache.storm.trident.operation.BaseAggregator;
import org.apache.storm.trident.operation.TridentCollector;
import org.apache.storm.trident.tuple.TridentTuple;
import org.apache.storm.tuple.Values;
import java.util.HashMap;
import java.util.Map;
public class WordAggregat extends BaseAggregator<Map<String, Integer>> {
public static Map<String, Integer> map = new HashMap<String, Integer>();
@Override
public Map<String, Integer> init(Object batchId, TridentCollector collector) {
return new HashMap<String, Integer>();
}
@Override
public void aggregate(Map<String, Integer> val, TridentTuple tuple,TridentCollector collector) {
String location = tuple.getString(0);
Integer i = map.get(location);
if(null == i){
i = 0;
}else{
i = i+1;
}
map.put(location, i);
}
@Override
public void complete(Map<String, Integer> val, TridentCollector collector) {
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}
collector.emit(new Values(map));
}
}
（1）init 接收第一batch 执行
（2）aggregate循环执行
（3）complet结束循环执行
Trident构建
package com.storm.topology;
import com.storm.spout.FixedBatchSpout;
import com.storm.trident.Split;
import com.storm.trident.WordAggregat;
import com.storm.trident.WordFilter;
import org.apache.storm.Config;
import org.apache.storm.LocalCluster;
import org.apache.storm.generated.StormTopology;
import org.apache.storm.redis.common.config.JedisClusterConfig;
import org.apache.storm.redis.trident.state.RedisClusterState;
import org.apache.storm.trident.TridentTopology;
import org.apache.storm.trident.operation.builtin.Count;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Values;
import java.net.InetSocketAddress;
import java.util.HashSet;
import java.util.Set;
public class TTopology {
public static void main(String[] args){
TridentTopology topology = new TridentTopology();
FixedBatchSpout spout = new FixedBatchSpout(new Fields("sentence"), 1,
new Values("the cow jumped over the moon"),
new Values("the man went to the store and bought some candy"),
new Values("four score and seven years ago"),
new Values("how many apples can you eat"));
spout.setCycle(true);
topology.newStream("batch-spout",spout).parallelismHint(2)
.each(new Fields("sentence"), new Split(), new Fields("word")).project(new Fields("word")) //project方法只发送word字段
.aggregate(new Fields("word"),new WordAggregat(),new Fields("agg"));
StormTopology stormTopology = topology.build();
LocalCluster cluster = new LocalCluster();
Config conf = new Config();
conf.setDebug(true);
cluster.submitTopology("soc", conf,stormTopology);
}
}
project方法作用是摒弃tuple其他消息体，之发送word一个field
结果
出现单词的次数
